Tray controlling method using firmware for detecting different inclined position

ABSTRACT

A tray control method for a disk drive including a tray for carrying a disk, a detect switch movable to different inclined positions for detecting different positions of the tray during tray ejection operation, a firmware for receiving signals transmitted by the detect switch upon reaching the different inclined positions. The voltage applied to the DC motor for moving the tray is adjusted based on the time difference between the signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/345,057, filed Dec. 29, 2008, now U.S. Pat. No. 7,817,503, andentitled TRAY CONTROLLING METHOD USING MULTIPLE DIFFERENT VOLTAGES, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a tray control method, and more particularly toa method for controlling tray ejection and retraction operations in adisk drive.

2. Description of the Related Art

Lately, as the electronic technology advances, optical disks are welcomemore and more due to its compact size, high storage capacity and longpreserving time for data. Prevalence of the optical disk raises the diskdrive to a high demand commodity in the electronic market.

A conventional disk drive generally includes a tray for carrying a diskand a DC motor for moving the tray to the retracted and ejectedpositions via a gear mechanism, thereby facilitating placing the disk onthe tray or removing the disk from the tray. The output force of the DCmotor for moving the tray depends on the applied voltage and the voltagelevel is generally controlled by the firmware of the disk drive.

In general, the force and speed for moving the tray to the retracted andejected positions depend on the applied voltage to the DC motor andfurther on the structural connection between the tray and the otherinterior mechanism, such as a traverse module, clamping mechanism andetc.

In the prior art technology, the engineers at the production factory usetry-and-error method to adjust the voltage applied to the DC motor inorder to provide stable vibration of the tray during the tray retractionand tray ejection operations in the disk drive. However, in the massproduction line, it is relatively difficult to use try-and-error methodon each of the disk drives, thereby failing to maintain the structuralconnection between the tray and the other interior mechanism at thedesired position, which, in turn, results in problems.

For instance, when the structural connection between the tray and theother interior components is loose, the force and speed for moving thetray to the retracted and ejected positions is relatively great, whichmay cause impact between the tray and the interior components, therebyshortening the service life of the disk drive or dropping the disk fromthe tray at the ejected position. When the structural connection betweenthe tray and the other interior components is tight, the force and speedfor moving the tray to the retracted and ejected positions is relativelysmall, which, in turn, will prolong the retracting and ejecting time forthe tray. The result fails to meet the requirement specification ofclients.

In the prior art technology, depending on presence or absence of thedisk on the tray, the firmware of the disk drive adjusts the voltageapplied to the DC motor, thereby altering the output force of the DCmotor for moving the tray.

When there is no disk on the tray, the clamping mechanism is locatedclosely to the holding seat so that relatively strong attraction isexisted among the interior components. A large force is required tospace the components apart or else the tray ejection operation cannot beperformed.

When the disk is disposed on the tray, the output force of the DC motoris required to be adjusted appropriately prior to the tray reaching theejected position. Otherwise, the impact of the tray against the outercasing upon reaching the ejected position will cause dropping the diskfrom the tray.

Due to the aforesaid reasons, the firmware of the retract-and-ejectsystem in the disk drive plays an important role for determining whetherthe disk is present or absent from the tray. For instance, the disk ispresent on the tray but the firmware determines that the disk is absentfrom the tray, the output force of the DC motor is too large and maydrive the tray at an undesired high speed that the disk may drop fromthe tray during the tray ejection operation. On the other hand, in casethe disk is absent from the tray, however the firmware determines thatthe disk is on the tray, the output force of the DC motor for moving thetray is too small to separate the clamping mechanism from the holdingseat so that the tray ejection operation cannot be performed.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a tray controlmethod, in which, a detect switch transmits a signal based on theposition of the tray so as to control the force and speed for moving thetray during the tray retraction and ejection operations. By altering thevoltage applied to the DC motor so as to control different output forcesfor moving the tray from one position to the other such that the trayslides stably during the tray retraction and ejection operations.

The other object of the present invention is to provide a tray controlmethod, in which, different signal is transmitted by the detect switchwhen the detect switch is shifted to different inclined positions basedon movement of the tray along a Z-shaped guiding channel in an up-downplate so as to adjust the firmware. Thus, the firmware can determinewhether the disk is present on the tray or not before the tray reachinga fully retraction position.

The tray ejection control method of the present invention is implementedin a disk drive that includes a tray for carrying a disk, a detectswitch, a DC motor and a firmware.

For tray ejection operation in the disk drive, a voltage is applied tothe DC motor to move the tray in sequence through a first position, asecond position, a third position to a fourth position meanwhile thedetect switch is correspondingly shifted in sequence through a firstinclined position, a second inclined position, a third inclined positionto a fourth inclined position.

When the detect switch is shifted to the second inclined position, afirst signal is transmitted to the firmware. When the detect switch isshifted to the third inclined position, a second signal is transmittedto the firmware. In this embodiment, in order to control the force atthe initial stage of the tray ejection operation and the tray ejectiontime, the following steps are conducted, that is:

supplying a first voltage for moving the tray during a first applicationtime;

raising the first voltage to a second voltage in order to move the traywhen the first application time is elapsed and the first signal is nottransmitted;

maintaining the second voltage during a second application time; and

receiving the first signal, wherein a total amount of the first andsecond application time is less than or equal to a predetermined time.

In other embodiment, the tray ejection control method of the presentinvention includes the following steps:

setting a first reference time and a second reference time, wherein thesecond reference time is greater than the first reference time;

calculating a time difference between a first interval time frombeginning ejection of the tray till the second signal is transmitted anda second interval time from beginning ejection of the tray till thefirst signal is transmitted when the second signal is transmitted; and

adjusting a voltage applied to a DC motor based on the time differencebetween the first and second interval time.

In another embodiment, the tray ejection control method of the presentinvention includes the following steps:

moving the tray from a first position to a second position by applying avoltage to a DC motor;

receiving a first signal;

maintaining the voltage applied to the DC motor for a specific timeafter receiving the first signal;

lowering the voltage; and

moving the tray to the fourth position.

After the first signal is received and when the specific time iselapsed, the voltage for moving the tray is lowered by the firmwarebefore reaching the fourth position (fully ejected position) so as toavoid an impact caused thereby.

A method for controlling tray retraction is provided according to thepresent invention and is implemented in a disk drive that includes atray for carrying a disk, a detect switch, a DC motor, a firmware and atraverse module.

A voltage is applied to the DC motor to move the tray in sequencethrough a fourth position, a third position, a second position to afirst position meanwhile the detect switch is correspondingly shifted insequence through a fourth inclined position, a third inclined position,a second inclined position to a first inclined position.

When the detect switch is shifted to the third inclined position, athird signal is transmitted to the firmware. When the detect switch isshifted to the second inclined position, a fourth signal is transmittedto the firmware. The tray retraction control method includes thefollowing steps:

moving the tray from the fourth position to the third position, whereinthe traverse module is disposed at a lower position;

receiving the third signal;

moving the tray from the third position to the second position, whereinthe traverse module is raised from the lower position to an upperposition;

receiving the fourth signal;

determining whether the disk is present on the tray or not; and

moving the tray from the second position to the first position.

When the tray is moved from the second position to the first position,the traverse module is disposed at the upper position. In other words,the traverse module is retained at the upper position during movement ofthe tray from the second position to the first position.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of this invention will become moreapparent in the following detailed description of the preferredembodiments of this invention, with reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic view illustrating relationship among a tray, anup-down plate and other mechanism in a disk drive;

FIG. 2 is an exploded view illustrating an outer casing, a traversemodule and an up-down plate in the disk drive;

FIG. 3 shows a top fragmentary view illustrating interior components ofthe disk drive;

FIGS. 4A to 4D respectively shows relationship and positions among atraverse module, the up-down plate and a detect switch in a disk driveof the present invention;

FIG. 5 is a graph representing the voltage applied to a DC motor and theapplication time during the tray ejection operation in the disk drive ofthe present invention;

FIG. 6 is a block diagram illustrating the control steps during initialstage of a tray ejection operation in the disk drive of the presentinvention;

FIG. 7 is a block diagram illustrating the steps for a first controlmethod during the final stage of the tray ejection operation in the diskdrive of the present invention;

FIG. 8 is a block diagram illustrating the steps for a second controlmethod during the final stage of the tray ejection operation in the diskdrive of the present invention; and

FIG. 9 is a block diagram illustrating the steps for a control method ofdetermining whether a disc is present on the tray or not during the trayretraction operation in the disk drive of the present invention.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 2 respectively illustrates interior components of disk drivesavailable in the market of today. FIG. 3 shows interior componentswithin an outer casing of the disk drive.

As illustrated in FIG. 1, the disk drive generally includes a tray 11for carrying a disk, an up-down plate 12 connected operationally to thetray 11 via rack-and-pinion mechanism (not shown) and a DC motor fordriving the tray 11. Activation of the DC motor causes movements of thetray 11 to the retracted and ejected positions, which, in turn, resultsin reciprocal movement of the up-down plate 12 to left-and-right sidesalong a horizontal direction.

As shown in FIG. 2, the disk drive further includes an outer casing 10receiving a traverse module 13 and the up-down plate 12, wherein theup-down plate is mounted in front of the traverse module 13.

The traverse module 13 has two guide rods 131 extending respectively andbeing slid into two Z-shaped sliding channels 121 in the up-down plate12. Movement of the up-down plate 12 along the horizontal directionresults in sliding action of the guide rods 131 in the Z-shaped slidingchannels 121, thereby raising or lowering the traverse module 13 toupper or lower positions.

When the traverse module 13 is raised to the upper position, a rotatingseat 14 located above the traverse module 13 retains the disk (notshown) stably thereon. The disk drive further includes a clampingmechanism opposite to the rotating seat 14, wherein the disk is retainedstably between the rotating seat 14 and the clamping mechanism. Sincethe rotating seat 14 and the clamping mechanism both have magneticmembers, a magnetic attraction is present therebetween to retain thedisk more stably.

FIG. 3 shows a top fragmentary view of the disk drive of the presentinvention, wherein the disk drive further includes a detect switch 15connected operationally to the tray 11 via a linkage mechanism so thatthe detect switch 15 is shifted to different inclined positions todetect relative positions of the tray 11 during the tray retractionoperation and tray ejection operation.

FIGS. 4A to 4D respectively shows relative positions of the guide rods131 of the traverse module 13 within the Z-shaped sliding channels 121in the up-down plate 12 during the tray ejection operation and the trayretraction operation and corresponding inclined position of the detectswitch 15.

FIG. 4A illustrates relative position of the corresponding mechanismwhen the tray 11 is at a first position (fully retracted position). Whenthe tray 11 is moved to the first position, the guide rods 131 of thetraverse module 13 are located at the leftmost side 121 a of the upperstraight section of the Z-shaped sliding channels 121 in the up-downplate 12. At this time, the traverse module 13 is retained at an upperposition while the detect switch 15 is shifted to a first inclinedposition 15 a. The first position indicates that the tray 11 isretracted fully within the disk drive.

Referring to FIG. 4B, when the tray 11 is moved to a second positionfrom the first position during the tray ejection operation, the up-downplate 12 moves to the left side of the casing along the horizontaldirection, thereby moving the guide rods 131 of the traverse module 13to the rightmost side 121 b of the upper straight section of theZ-shaped sliding channels 121 in the up-down plate 12. At this time, thetraverse module 13 is retained at the upper position while the detectswitch 15 is shifted from the first inclined position 15 a to a secondinclined position 15 b. The second position is close to the fullyretracted position.

Referring to FIG. 4C, when the tray 11 is moved to a third position fromthe second position during the tray ejection operation, the up-downplate 12 moves further to the left side, thereby pushing the guide rods131 of the traverse module 13 from the rightmost side 121 b of the upperstraight section of the Z-shaped sliding channels 121 downward along theinclined section of the Z-shaped sliding channels 121 to the leftmostside 121 c of the lower straight section of the Z-shaped slidingchannels 121. At this time, the traverse module 13 is consequently movedfrom the upper position to a lower position while the detect switch 15is shifted from the second inclined position 15 b to a third inclinedposition 15 c. The third position is close to the fully ejectedposition.

Referring to FIG. 4D, when the tray 11 is further moved to a fourthposition during the tray ejection operation, the up-down plate 12 movesfurther to the left side along the horizontal direction, thereby movingthe guide rods 131 from the leftmost side 121 c of the lower straightsection of the Z-shaped sliding channels 121 to the rightmost side 121 dof the lower straight section. At this time, the traverse module 13 isretained at the lower position while the detect switch 15 is shiftedfrom the third inclined position 15 c to a fourth inclined position 15d. The fourth position indicates that the tray 11 is ejected fullyoutward from the disk drive while the third position is close to thefourth position.

The aforementioned FIGS. 4A to 4D respectively shows the steps,structural connection and relative positions among the traverse module13, the up-down plate 12 and the detect switch 15 during the trayejection operation of the disk drive. In the same manner, FIGS. 4D to 4Arespectively shows the steps, structural connection and relativepositions among the traverse module 13, the up-down plate 12 and thedetect switch 15 during the tray retraction operation of the disk drive.

During shifting the detect switch 15 from the first inclined position 15a to the second inclined position 15 b, the detect switch 15 ismaintained at the switch-on state. A first signal is transmitted to thefirmware when the detect switch 15 is disposed at the second inclinedposition 15 b. The first signal is a switch-off signal. During shiftingthe detect switch 15 from the second inclined position 15 b to the thirdinclined position 15 c, the detect switch 15 is maintained at theswitch-off state. A second signal is transmitted to the firmware whenthe detect switch 15 is disposed at the third inclined position 15 c.The second signal is the switch-on signal. During shifting the detectswitch 15 from the third inclined position 15 c to the fourth inclinedposition 15 d, the detect switch 15 is maintained at the switch-onstate.

In the same manner, during shifting the detect switch 15 from the fourthinclined position 15 d to the third inclined position 15 c, the detectswitch 15 is maintained at the switch-on state. A third signal istransmitted to the firmware when the detect switch 15 is disposed at thethird inclined position 15 c. The third signal is a switch-off signal.During shifting the detect switch 15 from the third inclined position 15c to the second inclined position 15 b, the detect switch 15 ismaintained at the switch-off state. A fourth signal is transmitted tothe firmware when the detect switch 15 is disposed at the secondinclined position 15 b. The fourth signal is the switch-on signal.During shifting the detect switch 15 from the second inclined position15 b to the first inclined position 15 a, the detect switch 15 ismaintained at the switch-on state.

During the movement of the aforesaid tray 11, transmitting the signalsby the detect switch 15 at different inclined positions and movement ofthe guide rods 131 within the Z-shaped sliding channels 121 in theup-down plate 12 are applied to control the firmware. Thus, the voltagerequired for applying to the DC motor for moving the tray to differentpositions can be adjusted properly then the tray ejection and retractionoperations are more smooth and steady. A detailed disclosure thereof isgiven in the following paragraphs.

Summarizing the aforesaid movements of the hardware, for tray ejectionoperation, the DC motor is applied by a voltage to move the tray insequence through the first position, the second position, the thirdposition to the fourth position meanwhile the detect switch 15 iscorrespondingly shifted in sequence through the first inclined position15 a, the second inclined position 15 b, the third inclined position 15c to the fourth inclined position 15 d.

When the detect switch 15 is shifted from the first position 15 a to thesecond inclined position 15 b, a first signal is transmitted to thefirmware. When the detect switch 15 is shifted from the second position15 b to the third inclined position 15 c, a second signal is transmittedto the firmware, wherein the first signal is a switch-off signal whilethe second signal is a switch-on signal.

Referring to FIGS. 5 and 6, the method for controlling the voltage leveland the application time during the initial stage of the tray ejectionoperation, includes the following steps.

First, supply a first voltage V1 for moving the tray 11 during a firstapplication time T1 (S61), wherein the tray 11 is moved from the firstposition (fully retracted position) to the second position.

After elapse the first application time T1 and the first signal is notreceived, raise the first voltage V1 to a second voltage V2 in order tomove the tray 11 (S62). It means that since the components of the diskdrive are in tight structural connection, the first voltage V1 appliedduring the first application time T1 is unable to move the tray 11 tothe second position. A larger voltage is required so that the firmwareraises the first voltage V1 to the second voltage V2 to move the tray11. In this step, the firmware alters the first voltage V1 to the secondvoltage V2.

Then, maintain the second voltage V2 during a second application time T2(S63).

After elapse the second application time T2, and the first signal is notreceived, raise the second voltage V2 to a third voltage V3 in order tomove the tray 11 (S64). During the second application time T2, thesecond voltage V2 is unable to move the tray 11 to the second positionmeans that the mechanism of the disk drive are in tight structuralconnection. Avoiding the tray ejection operation is too slowly, a largervoltage is required to move the tray 11. In this step, the firmwarealters the second voltage V2 to the third voltage V3.

Maintain the third voltage V3 during a third application time T3 (S65).

Later, receive the first signal, wherein a total amount of the first,second and third application time is less than or equal to apredetermined time Td (S66). During this step, the tray 11 is moved tothe second position while the detect switch 15 is consequently shiftedto the second inclined position 15 b and transmits the first signal tothe firmware.

Since the structural connection among the components in one disk drivediffers from the other disk drive, in other embodiment, maybe only thesecond voltage V2 is required to move the tray 11 to the second positionduring the predetermined time Td.

Therefore, in the aforesaid method, during movement of the tray 11 fromthe first position to the second position, the voltage and theapplication time are adjusted in order to compensate the tight and loosestructural connection among the components, thereby controlling the trayejection time within the predetermined time. Thus, the tray ejectiontime does not take too long.

FIG. 5 is a graph representing the voltage applied to a DC motor and theapplication time while FIG. 7 is a block diagram illustrating the stepsfor a first control method during the final stage of the tray ejectionoperation in the disk drive of the present invention. The first controlmethod includes the following steps.

Set a first reference time Tf1 and a second reference time Tf2, whereinthe second reference time Tf2 is greater than the first reference timeTf1 (S71).

Calculate a time difference between a first interval time (Tsw=on) frombeginning ejection of the tray till the second signal is transmitted anda second interval time (Tsw-off) from beginning ejection of the traytill the first signal is transmitted when the second signal istransmitted (S72). It is to find out the time difference for moving thetray 11 from the first position to the third position minus the time formoving the tray 11 from the first position to the second position. Atthis time, the tray 11 is disposed at the third position close to thefourth position (fully ejected position).

Then, adjust the voltage for applying to the DC motor based on the timedifference (Tsw-on−Tsw-off) between the first and second interval time(S73).

In case the time difference (Tsw-on−Tsw-off) is smaller than the firstreference time (Tf1), it means that the structural connection among thecomponents is rather loose. The firmware will lower the voltage appliedto the DC motor, illustrated as line A in FIG. 5. Under this condition,the occurrence of dropping the disk from the tray due to large impactupon reaching the fully ejected position (the fourth position) can beavoided.

In case the time difference (Tsw-on−Tsw-off) falls between the firstreference time Tf1 and the second reference time Tf2, it means that thestructural connection among the components is normal such that thefirmware supplies and maintaining the voltage initially applied on theDC motor, as shown by line B in FIG. 5.

When the time difference (Tsw-on−Tsw-off) is greater than the secondreference time Tf2, it means that the structural connection among thecomponents is rather tight such that the firmware raises the voltageapplied to the DC motor, as shown in line C in FIG. 5. Thus, the trayejection time is restricted within the predetermined time.

In the aforesaid method, during movement of the tray 11 from the secondposition to the third position, the voltage and the application time areadjusted for the second time in order to compensate the tight and loosestructural connection among the components, thereby controlling the trayejection time and the voltage applied to the DC motor. In oneembodiment, the steps shown in FIGS. 6 and 7 are combined together tocontrol the tray ejection operation.

FIG. 8 is a block diagram illustrating the steps for a second controlmethod of the present invention during the final stage of the trayejection operation in the disk drive. The second control method differsfrom the first control method and includes the following steps.

First, move the tray 11 from the first position to the second positionby applying a voltage to the DC motor (S81).

Receive the first signal (S82).

Maintain the voltage on the DC motor for a specific time after receivingthe first signal (S83).

Lower the voltage (S84).

Move the tray 11 to the fourth position (S85).

It is to say that after receiving the first signal, the voltage ismaintained for a specific time, such as for 450 milliseconds.Afterwards, the firmware lowers the voltage applied to the DC motor formoving the tray 11, wherein before the tray 11 reaching the fourthposition, the voltage is lowered in order to avoid impact of the trayagainst the outer casing during the tray ejection operation.

Therefore, in the aforesaid method, it is to slow down the movement ofthe tray 11 during the final stage of the tray ejection operation in thedisk drive. In one embodiment, the steps shown in FIGS. 6 and 8 arecombined together to control the tray ejection operation.

FIG. 9 is a block diagram illustrating the steps for a control method ofthe present invention during the tray retraction operation in the diskdrive. For tray retraction operation, the DC motor is applied by avoltage to move the tray 11 in sequence through the fourth position, thethird position, the second position to the first position meanwhile thedetect switch 15 is correspondingly shifted in sequence through thefourth inclined position 15 d, the third inclined position 15 c, thesecond inclined position 15 b to the first inclined position 15 a.

When the detect switch 15 is shifted to the third inclined position 15c, a third signal is transmitted to the firmware. When the detect switch15 is shifted to the second inclined position 15 b, a fourth signal istransmitted to the firmware. During the tray retraction operation, thethird signal is a switch-off signal while the fourth signal is aswitch-on signal.

The tray retraction control method accordingly includes the followingsteps.

Move the tray 11 from the fourth position to the third position, whereinthe traverse module 13 is disposed at a lower position (S91). In thisstep and during movement of the tray 11 from the fourth position to thethird position, the up-down plate 12 moves along a horizontal directionto the right side of the outer casing, in which the guide rods 131 aremoved from the rightmost side 121 d to the leftmost side 121 c in thelower straight section of the Z-shaped guiding channels 121 in theup-down plate 12. The traverse module 13 is maintained at the lowerposition.

Receive the third signal (S92). In this step, when the tray 11 is movedto the third position, the detect switch 15 is correspondingly shiftedto the third inclined position 15 c while the third signal istransmitted to the firmware.

Move the tray 11 from the third position to the second position, whereinthe traverse module 13 is raised from the lower position to an upperposition (S93). In this step, movement of the up-down plate 12 to theright side of the outer casing results in raising the guide rods 131from the leftmost side 121 c to the rightmost side 121 b of the inclinedsection of the Z-shaped guiding channels 121 in the up-down plate 12. Atthis time, the traverse module 13 is raised from the lower position tothe upper position.

Receive the fourth signal (S94). In this step, the tray 11 is moved tothe second position while the detect switch 15 is accordingly shifted tothe second inclined position 15 b. The fourth signal is transmitted tothe firmware in the disk drive. Then, the firmware determines whetherthe disk is present on the tray 11 or not (S95). In this step, thefirmware further finds out the type of disk and dimension of the diskwhen receiving the fourth signal. So that the firmware can make an earlydetermination of the disk with respect to the tray 11 prior to the tray11 reaching the fully retracted position (the first position)

Afterward, move the tray 11 from the second position to the firstposition, wherein during movement of the tray 11 from the secondposition to the first position, the traverse module 13 is maintained atthe upper position (S96).

In the aforesaid method, before the tray reaching the fully retractedposition, the firmware can make an early determination of the disk withrespect to the tray so as to avoid the problems (such as forcefulcollision) caused in the earlier prior art technology.

In addition, by determining the dimension of the loaded disk, thefirmware is able to control the voltage applied to the DC motor duringthe tray ejection. When the loaded disk has a smaller dimension, theapplied voltage to the DC motor during the tray ejection is smaller thanthe larger dimension disk on the tray so that the smaller dimension diskis not dropping from the tray at the fourth position. When the loadeddisk has large dimension, the applied voltage is higher than the smallerdimension disk so that the applied voltage is able to move the tray.

While the present invention has been described in connection with whatis considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

1. A method for controlling tray ejection of a disk drive that includesa tray for carrying a disk, a detect switch, a DC motor and a firmware,wherein a voltage is applied to the DC motor to move the tray insequence through a first position, a second position, a third positionto a fourth position meanwhile the detect switch is correspondinglyshifted in sequence through a first inclined position, a second inclinedposition, a third inclined position to a fourth inclined position,wherein a first signal is transmitted to the firmware when the detectswitch is shifted to the second inclined position, and a second signalis transmitted to the firmware when the detect switch is shifted to thethird inclined position, the tray ejection control method comprising thefollowing steps: setting a first reference time and a second referencetime, wherein said second reference time is greater than said firstreference time; calculating a time difference between a first intervaltime from beginning ejection of the tray till said second signal istransmitted and a second interval time from beginning ejection of thetray till said first signal is transmitted when said second signal istransmitted; and adjusting the voltage applied to the DC motor based onsaid time difference between said first and second interval time.
 2. Thetray ejection control method according to claim 1, further comprisingthe step of: lowering the voltage applied to the DC motor in case saidtime difference is smaller than said first reference time.
 3. The trayejection control method according to claim 1, further comprising thestep of: maintaining the voltage applied to the DC motor in case saidtime difference is between said first reference time and said secondreference time.
 4. The tray ejection control method according to claim1, further comprising the step of: raising the voltage applied to the DCmotor in case said time difference is greater than said second referencetime.
 5. The tray ejection control method according to claim 1, whereinduring the tray ejection of the disk drive, said first signal is aswitch-off signal while said second signal is a switch-on signal.
 6. Thetray ejection control method according to claim 1, wherein said firstposition indicates that the tray is retracted fully within the diskdrive, said fourth position indicates that the tray is ejected fullyoutward from the disk drive while said third position is close to thefourth position and said second position is close to said thirdposition.